The present invention relates first to an illumination device for an observation device having one, two or more observation beam paths, having an observation light bundle for each path, having a least one light source for producing at least one illumination light bundle for illuminating an object to be observed, in particular, an eye to be observed, wherein at least two partial illumination light bundles are provided and wherein each partial illumination light bundle runs coaxially to a corresponding observation light bundle and also relates to an illumination device for an observation device having one, two or more observation beam paths, having an observation light bundle for each path, having at least one light source for producing at least one illumination light bundle for illuminating an object to be observed, in particular, an eye to be observed. In addition, the invention relates to an observation device, in particular, an operating microscope, having one, two or more stereoscopic observation beam paths, having an observation light bundle for each path, and having an illumination device, having at least one light source for producing at least one illumination light bundle for illuminating an object to be observed, in particular, an eye to be observed, wherein at least two partial illumination light bundles are provided and wherein each partial illumination light bundle runs coaxially to a stereoscopic observation light bundle and also relates to an observation device, in particular, an operating microscope, having one, two or more stereoscopic observation beam paths, having an observation light bundle for each path, and having an illumination device, having at least one light source for producing at least one illumination light bundle for illuminating an object to be observed, for example, an eye. In addition, the invention relates to the use of the above illumination device in an operating microscope, in particular, in an ophthalmologic observation device, preferably in an operating microscope designed for cataract extraction and to the use of the above observation device as an operating microscope, in particular, as an ophthalmologic observation device, preferably as an operating microscope designed for cataract extraction.
For example, an observation device may involve an operating microscope. In particular, the observation device can be designed as an ophthalmologic operating microscope, which is utilized, for example, for a special application in eye surgery, i.e., cataract surgery.
In the case of cataract surgery, a lens of the eye—which is clouded, for example, due to the cataract—is replaced by an artificial lens.
The lens of an eye is found inside a thin envelope, the so-called lens capsule. In order to remove the lens of the eye, access to it is created by a thin cut made in the lens capsule and the lens of the eye is first broken up into small pieces with a microsurgical instrument, and then these pieces are removed by means of an aspirating device.
This process takes place under microscopic observation—for example, under stereomicroscopic observation—employing a specially designed illumination device for such interventions. This illumination device presents both an illumination of the surrounding field, which is necessary for illuminating the entire operating field, as well as a red background illumination for the actual operating field limited to the pupil region of the lens of the eye, which is of decisive importance for the cataract operation. This red background illumination is derived from the fraction of illuminating light, which, after passing through the transparent media of the eye, finally strikes the retina, which appears red due to good blood perfusion, is back-scattered therefrom, and then can be observed, of course, as an apparent red background illumination by the surgeon also by means of the operating microscope. This very characteristic red background illumination in cataract surgery is generally known in the profession under the term “red reflex”.
For an optimal recognition of details relevant to the cataract operation, a red background illumination that is as homogeneous as possible has been proven to be a necessary prerequisite for the surgeon. A first requirement of the illumination device is thus to assure a homogeneity of the red reflex that is as optimal as possible over the entire pupil of the patient.
For complete elimination of the pieces of the lens of the eye which has been broken up into tiny pieces and for good recognition of transparent membranes, for example, of the lens capsule, another requirement must be fulfilled, that is, there must be a good contrasting of phase objects and in fact, this contrast should also be provided as much as possible over the entire pupil of the patient.
In the past, various solutions have already been made known in connection with the production of such red background illumination.
In U.S. Pat. No. 4,779,968, a coaxial illumination for an operating microscope is described. According to this solution, a lighting module is provided, which can be subsequently incorporated as an additional module in existing operating microscopes. This additional module is preferably introduced on the object side underneath the principal objective of the observation device. The illumination is coupled onto the axis of the microscope either with a beam-splitter plate or a beam-splitter cube.
An illumination device for an operating microscope is described in DE 4,028,605 C2, which permits a combination of zero-degree, coaxial and oblique illumination. For this purpose, the illumination device makes available movable sub-mirrors as well as a stationary six-degree mirror plus the respective variable diaphragms, by which means the angle of illumination and the lighting components of the respective illumination device can be varied. The emphasis of this known solution lies in increasing the contrast by means of a coaxial illumination, wherein this coaxial illumination involves an oblique illumination found near the axis.
An ophthalmologic observation device is disclosed in DE 196 38,263 A1, in which the unavoidable corneal reflex that occurs when a patient's eye is illuminated for observation of the front segments of the eye will be suppressed. This is performed by introducing a light absorber in the form of a black point in the vicinity of a luminous-field diaphragm of an otherwise known illumination.
A reversible illumination system for an ophthalmologic operating microscope is described in U.S. Pat. No. 6,011,647, in which the system can be switched between a surrounding-field illumination and an optimized “red reflex” illumination during the operation. The illumination device is comprised of a light source, a collector, a luminous-field diaphragm, a tilting mirror, a field lens and a principal objective. In the case of this optimized “red reflex” illumination, the helix of the light source is then imaged or mapped in the pupil of the eye as the object plane, and not the luminous-field diaphragm as is the case with surrounding-field illumination.
In EP 1,109,046 A1, an illumination device for an operating microscope is disclosed, which has two reflection elements that can be moved independent of one another, by means of which both the angle of the incident light with the optical axis of the microscope objective as well as the intensity of the different light beams can be changed independent of one another.
For surgery on the eye, and here, in particular, in cataract operations, a homogeneous, bright “red reflex” is required along with a good contrasting of phase objects over the entire region of the patient's pupil.
The operating microscopes of the prior art fulfill these requirements for regions of the pupil that are of varying size. A compromise must always be found between the primary requirements of a good, homogeneous “red reflex” and a good contrasting of phase objects.
For the most part, illumination is produced at a small angle for observation. This has the consequence, however, that the “red reflex” does not appear uniformly bright over the patient's pupil. An illuminating angle between 2 and 4 degrees has previously proven favorable. At this angle, one obtains a good compromise between good contrasting and illumination of the patient's pupil. With this arrangement, however, the “red reflex” reacts sensitively to a rolling of the patient's eye during the operation.
Tests with coaxial illumination in fact led to a good, homogeneous “red reflex”, but to a poor contrasting of phase objects, and thus previously have not proven suitable in practice. In this case, the illuminating optics were disposed such that an illuminating mirror (or prism) lay between the two beam paths of the stereomicroscope. In this case, therefore, a precise 0° illumination, which is accurately produced from the same direction as the observation, was not provided.
Finally, an illumination device for operating microscopes is described in DE 4,417,273 A1, in which the illuminating light bundle is divided into at least two partial illuminating light bundles, wherein each partial illuminating light bundle of the illuminating beam runs coaxially to an illuminating light bundle. In this way, the “red reflex” will be improved.